1. Field of the Invention
The present invention relates to a method of storing data in an internal storage device included in a process controller for a machine, such as an injection molding machine or the like, and to an internal storage device carrying out the method. More particularly, the present invention relates to a method of storing data in an internal storage device which stores data in divided storage areas so that a user can easily change data that are specific to the machine when necessary.
2. Description of the Related Art
A process controller of an injection molding machine or a die casting machine controls a series of operations including a mold closing operation and an injection molding operation. The process controller reads molding condition data stored in a storage device and controls the injection rate, injection pressure, screw speed, screw back pressure, mold opening and closing speed and heater temperature, etc.
The process controller of an injection molding machine has an internal storage device including a PROM and a RAM, and an external storage device which is optionally employed for writing data of molding conditions into a store in a batch.
The internal storage device stores programs and parameters. The parameters include molding condition data such as speed, pressure, temperature, position and time data, necessary for controlling process conditions, and history data including records of operations of the injection molding machine and molding condition setting histories, and data relating to characteristic values specific to the injection molding machine including the parameters of the control system.
The molding condition data are to be set by a user, and are changeable because different molds and different resins need different molding conditions.
The parameters of the control system are data specific to the injection molding machine and are not subject to change from initial setting values.
In a memory of a process controller, it is usual to store the molding condition data, the history data and the machine specific data in that order into three-level hierarchical storing areas from low-level addresses upward, respectively.
Some data which are substantially specific machine parameters are stored in the memory as the molding condition data.
PID parameters are examples of this kind. When controlling the temperature of the barrel heater of an injection molding machine by PID actions, an actuating signal is controlled by comparison of a set value and a feedback value. Since the set parameters for PID actions are those representing the characteristics of a control system, the set parameters for PID action are regarded as parameters to the injection molding machine rather than the mere molding condition data. On the other hand, the set parameters have the attribute of molding condition data which needs to be changed when mechanical specifications of the injection molding machine or the resin is changed. Therefore, the set parameters for PID actions are set not so much as specific machine data but as molding condition data in the conventional way.
Similarly, a printer connected to the controller that prints out the set data has printer setting parameters unique to its type.
In addition, the manufacturer of an injection molding machine carries out prescribed performance tests to verify the performance of the injection molding machine before shipment. After finishing the performance test, data used for the test must be cleared for initialization to delete memory contents for shipment. If the molding condition data includes set PID parameters, the set PID parameters are deleted through initialization. The set PID parameters are to be reentered by a manual operation into the internal storage device.
There is a case where the initialization for the data is required due to a malfunction of the molding machine. In this case, the memory contents of the machine specific data are deleted, and the same data must be restored in the storage device.
If the set PID parameters are not included in the molding condition data but in the machine specific data, the user is obliged to rely upon a service engineer to change the set PID parameters, because the storage area allocated for the machine specific data is not accessible to the user.
Since the machine specific data are not to be accessible to the user in a conventional process controller, when the user wants to reset the contents of memory storing machine specific data, the user can not select the machine specific data exclusively for the initialization. In such a case, the molding condition data stored in the low-level storage areas available to the user are initialized with the machine specific data at the same time. Therefore, when initializing the internal storage device, the molding condition data must temporarily be transferred to an external storage device, otherwise the molding condition data is deleted. Generally, an abnormal condition that requires resetting of stored machine specific data does not allow an opportunity to store the molding condition data in the external storage device. Therefore, the molding condition data cannot be stored in the external storage device and is bound to disappear. To make the system return to the normal condition, all the molding condition data needs to be reentered.